The Internet Protocol Television (IPTV) video service is a high bandwidth service, which is required to have a low packet loss ratio due to the high requirements for the real time performance. However, the network bandwidth, especially user link bandwidth, is generally rather limited. Therefore, in order to ensure the effective implementation of the video service and guarantee the service quality, a resource and admission control subsystem (RACS) needs to be deployed in the network.
The IPTV service includes a multicast/broadcast video service (for example, Broadcast Television (BTV)) and a unicast video service (for example, Video on Demanding (VOD)). Since the multicast service mode is significantly different from the unicast service mode, Admission Control (AC) functions thereof are implemented in quite different ways.
Besides the unicast video service such as VOD, various unicast service flows also exist, including services that have certain requirements for resources such as bandwidth, priority, or quality of service (QoS), for example, video telephony, VOIP, and web conference. All the services require AC and QoS guarantee.
The multicast AC is generally realized in an Access Node (AN). Specifically, the AN determines whether the user link bandwidth or multicast bandwidth meets the bandwidth requirement of a request for joining a channel, or determines whether the number of channels which the user has joined exceeds an upper limit. If the user link bandwidth is insufficient or the number of channels which the user has joined exceeds the upper limit, it indicates that the AC requested by the user fails, and the AN rejects the channel join request from the user.
The unicast AC function is generally implemented by an independent RACS. The RACS knows about the network topology, and manages an end-to-end bandwidth from a unicast video server to a user. Therefore, when the user requests a unicast video service, the service server requests resources from the RACS, the RACS determines whether the end-to-end bandwidth meets the requirement, and returns a resource request result, and then the service server determines whether to admit the service according to the resource request result.
Based on the above multicast and unicast service modes, the multicast/unicast AC function requested by the user can be implemented through two solutions in the prior art.
In technical solution 1, on a user link, resources are respectively reserved for a multicast service and a unicast service, so that the resources reserved for the multicast service cannot be occupied by the unicast service and the resources reserved for the unicast service cannot be occupied by the multicast service. That is, the AN implements the local multicast AC function, and the RACS implements the end-to-end AC function from the unicast video server to the user. In this technical solution, the unicast AC function and the multicast AC function are independent from each other, and do not interfere with each other.
In technical solution 2, when the user requests to join a certain channel, the AN actively reports information about the channel which the user joins, and sends the information to the RACS directly or through a broadband network gateway (BNG). Then, the RACS determines whether the user link bandwidth meets the requirements, and if not, the RACS notifies the AN to reject the join request from the user. In this technical solution, the joining information of the multicast user is reported by the AN, and the AN does not have the multicast AC function, so that the RACS performs the AC operation uniformly, including both unicast and multicast.
During the implementation of the present invention, the inventor found that the prior art at least has the following problems.
For example, in the technical solution 1, the multicast service and the unicast service cannot share the bandwidth resources, which results in the waste of the bandwidth resources, and the technical solution 1 is merely applicable to scenarios where the user link bandwidth is sufficient.
In the technical solution 2, although the AN reports the joining information of the multicast user, and the RACS performs uniformly AC operation, and the multicast and the unicast are unified, this solution is rather complicated. Moreover, as a switching frequency of the multicast service is greater than that of the unicast service, a large amount of information exchange between AN and RACS may be caused when a large number of TV users frequently switch the channels, resulting in an extremely high requirement for the performance of the AN. Furthermore, the channel switching of the multicast service requires the AN to report the joining information of the multicast user and to interact with the RACS, so that the delay of the channel switching is quite long, and the user experience is rather poor, thereby reducing the utilization of the bandwidth resources.